The subject invention is directed toward the valve art and, more particularly, to an improved packing system for valve stems.
The invention is especially suited for use on ball valves and will be described with reference thereto; however, as will become apparent, the invention is capable of broader application and could be used on many different types of rotary valves.
Valves intended for use in systems handling highly toxic and dangerous fluids present special safety requirements. Leakage of any sort is, of course, unacceptable. To the extent possible, welded body construction to eliminate potential leak paths has been used. Similarly, redundant valves have sometimes been used to reduce problems with leakage past the valve seats.
One area of valve and system design which has presented special problems is with respect to valve stem packings. Welding and the use of simple static seals cannot generally provide a solution because of the need for relative movement between the stem and the valve body. While various diaphragm and bellows seals have been used, these are often extremely complex, expensive, and if ruptured can produce a sudden, relatively large and uncontrollable leak.